The study was conducted to determine the use of hay, grass silage, corn silage and grass silage+corn silage as roughage sources on growth performance, some rumen and blood serum parameters in beef cattle. A total of 24 Simmental beef cattle (12 male, 12 female), 9 or 10 months age, which were initially 142.4 kg live weight, were used in this study. The animals were divided into four treatment groups each consisting of 6 cattle (3 male, 3 female). All animals in the groups were fed with 2888 g for 0-21 d, 3813 g for 22-42 d and 5177 g for 43-63 d concentrated feed. In addition to the concentrated feed, one of the following roughage source hay, grass silage, corn silage or grass silage+corn silage (50: 50) were given ad libitum to animals in each group. Animals were fed by group basis. At the 63 d of the study, rumen fluid and blood serum samples were taken from the animals. Final live weights of the animals did not affect. Average daily weight gains of the cattle in the overall study were no statistical differences among the groups. The roughage sources did not affect rumen fluid pH, NH3 N, acetic-, propionic-and butyric acid concentrations of beef cattle. The roughage sources did not also affect serum glucose, total protein and albumin concentration of animals. Consequently, it is concluded that mentioned roughage sources could be preferred as alone or grass silage+corn silage combination in feeding of beef cattle after economic analyses of these feedstuffs.